A moat and at least two rings of fences separate the public there from the endangered carnivores, the same species that killed a Whitehall, Allegheny County, toddler Nov. 4 at Pittsburgh Zoo & PPG Aquarium.

At the Audubon Zoo in New Orleans, two of three viewing areas for painted dogs keep visitors behind glass. The third — an open overlook area — features an outer wall, a roughly 3-foot gap and an inner cantilevered wall to secure the wildlife.

"They can be aggressive just like lions, tigers and bears can be," said Rick Dietz, vice president and general curator at the Audubon Zoo. "They do have a tendency to have a pack mentality when they're together" and feeding.

Zookeepers who oversee some of the 63 painted dogs at 37 zoos nationwide would not criticize the Pittsburgh Zoo's exhibit, where Maddox Derkosh, 2, tumbled from the railing of an observation deck and into the enclosure. Experts said the zoo, accredited by the Association of Zoos and Aquariums, looks generally well designed and prepared.

Yet, zoo management experts say, Maddox's death might bring changes at zoos, which have moved to shed traditional cages and adopt more-natural, open-space designs, some of which bring visitors face-to-face with wild animals.

"It will — it does — affect every single zoo. … It puts everybody on alert," said Richard J. Snider, a zoology professor at Michigan State University. "I'm sure there are already sketches being made here and there to prevent this."

At least one person who witnessed the death says the zoo should have made the exhibit safer. District Attorney Stephen A. Zappala Jr. said his investigation will include a review of safety procedures at the Highland Park zoo.

"One thing is for sure, [the safety] situation has to change," he said.

The AZA accreditation commission will comb through the design details again after the zoo files an incident report.

"These are safe places for children and families," he said. "People should know they're safe going to an accredited zoo."

Dietz said the dog exhibit in Pittsburgh, similar to some exhibits in other cities, "proved to be successful for many years."

"I think the exhibit was designed appropriately," he said. "At some point, the guests need to use common sense and not put themselves in danger."

Eleven dogs attacked Maddox after the youngster fell from atop a railing, where police say his mother, Elizabeth Derkosh, 33, had lifted him. He fell about 14 feet, bouncing off a mesh barrier that zoo officials said is for catching debris from the observation deck. It was the zoo's first visitor death from an animal since it opened in 1898.

The zoo shuttered the exhibit while it quarantines the dogs.

The Derkoshes, who buried Maddox on Friday, declined to comment.

Police said they have not yet interviewed the family and zoo officials.

Joshua Bloom, 41, of Fox Chapel, who witnessed the attack with his two young children, isn't convinced of the exhibit's safety. He called its design "grossly negligent."

"There shouldn't be any direct access," said Bloom, a lawyer. Netting under the deck gave people a false sense of security, and many parents hold their children up to see what the kids think are "cute doggies," he said.

"This was inevitable," Bloom said. "It really, really makes the trauma worse for me. This was going to happen to a family. This could happen to the best parents."

Zoo CEO Barbara Baker said last week the railing atop the observation deck was designed so that someone on top of it would fall back into the deck, away from the exhibit.

Bloom recalled "screaming so loud, I would imagine you could hear us from miles away. People were yelling, and no one was coming. No one was there."

Bloom said he ran to find help from the zoo. He saw a worker at the cafeteria, but "he didn't know how to react, what to do."

At least five minutes passed, Bloom estimated, before he heard employees blowing whistles. At that point, he and another father were warning parents near a walkway to turn around and leave.

"I just could not believe this was happening, and there was nobody from the zoo to respond," Bloom said. "They were not ready for this."

Zoo spokeswoman Tracy Gray said a zookeeper who was 10 feet away immediately responded by calling co-workers for help. Another keeper in the painted-dog building called for the dogs to get them inside, she said. She declined further comment.

Zoo leaders said a worker got seven of the dogs into the building and another keeper brought three in. At some point, they said, workers fired empty tranquilizer darts at the remaining dog that would not leave Maddox alone.